Network System

ABSTRACT

In a network system in which a large number of terminals that transmit information exist and data extraction is performed via a wide area network, when data filtering is performed by using terminals called entrance nodes, existing in front of the wide area network, efficient operation of the entrance nodes is a goal to achieve. In one implementation, when an entrance node has detected an alteration to a configuration of diverse resources attached to it, it updates management information by communicating with other entrance nodes existing in the neighborhood. In a further implementation, through a query and reply exchange about allocations of filtering and quick response processes to be executed by entrance nodes, reallocating process items, pre-filtering of necessary data, and relaying data between entrance nodes are performed.

CLAIM OF PRIORITY

The present application claims priority from Japanese patent applicationJP2011-82402 filed on Apr. 4, 2011, the content of which is herebyincorporated by reference into this application.

BACKGROUND OF THE INVENTION

The technical field of the present invention relates to a communicationsystem, in particular, a monitoring system that monitors communicationcontents at a network node.

Along with the dissemination of networks, a large-scale network systemis under consideration with the aim of mutually sharing information forplural network systems and creating new values. In such a large-scalenetwork system, due to growing network traffic and more complicatedapplications, current network nodes have been provided with thecapability of implementing more highly functional processes, as setforth in Japanese Patent Application Laid-Open Publication No.2007-26303, besides the ability of simple packet forwarding.

As an example of using network nodes that carry out highly functionalprocesses, a network that realizes quicker response by havingcomputational processing performed by a processing entity in a networkbetween user terminals and a data center is under consideration. As anexample of this type of network, there is a cloud-type network as setforth in Hidetaka Aoki, Hiroaki Shikano et al. “Cloud Architecture forTight Interaction with the Real World and Deep Sensor-Data AggregationMechanism”, 36-27882-2309 SoftCOM 2010. Highly functional network nodesconstituting the cloud-type network realize efficient traffic handlingand the execution of computational processing on behalf of a processingentity in the network by performing filtering processing andcomputational processing on data destined toward the data center.

Highly functional network nodes are located at end points of a wide areanetwork and perform monitoring and filtering of traffic, therebytransmitting data only required for a higher level system onto the widearea network, thus reducing the load of the wide area network. Thehighly functional network nodes serving as above, located at the endpoints of the wide area network, are called entrance nodes. Moreover, inthis network system, substitutive execution of a part of computationalprocessing by the entrance nodes enables the realization of response ina shorter time, dispensing with communication via the wide area network.

In order to realize traffic monitoring and filtering, as noted above, orquick response processing for achieving a shorter response time bysubstitutive execution of a part of computational processing, anentrance node performs the management of terminals attached to it andthe management of its own resources. Each entrance node holds, forexample, information about which entrance node is connected to which endnodes, the end nodes having sensors that transmit data and operatingactuators, and information about which entrance node is responsible forfiltering processing on traffic transmitted by the end nodes.Transversal management of such items of information is performed in sucha way that an administrative server existing on a higher levelcommunicates with plural entrance nodes transversally.

BRIEF SUMMARY OF THE INVENTION

In traditional networks, connections between an entrance node and itsattached nodes are statically configured. In a case that these nodesmoves, the administrative server collects information about newconnection destinations to which the nodes moved and traces movedterminals by a method such as updating management information on both adestination entrance node to which they moved and a source entrance nodefrom which they moved. Consequently, in traditional network systems,there is a first problem; when an alteration is made to the connectionsbetween an entrance node and its attached nodes connected to theentrance node, that is, the locations and connection destinations of theattached nodes, because of physical movement of some nodes, load may beconcentrated on the administrative server, so that the sever cannot copewith the alteration sufficiently.

Further, there is a second problem. A traditional entrance node onlyperforms filtering processing on information transmitted from terminalsmanaged by it. When terminals managed by entrance nodes relocate,processing may be concentrated on a particular entrance node. Oneentrance node may experience a decrease in processing speed or cannothandle all requests due to overload, whereas another entrance node mayhave nothing to be processed and waste its computational performance.

To address at least any one of the above two problems, in one aspect ofthe present invention, the following steps are performed. A networknode, upon receiving a packet, decides whether it holds informationabout the packet. If the network node does not hold this information, itsends a query to some other entrance node and determines a process itemin the packet. According to this determination, the network nodetransfers the packet to some other entrance node and entrusts acomputational process to the some other entrance node or the networknode executes the computational process by itself and transfers a resultof the processing.

According to one aspect of the present invention, packet transferprocessing can be performed efficiently.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of a network system using entrance nodes;

FIG. 2 is a diagram of a network system after terminals moved;

FIG. 3 is a diagram of a network system in which direct communicationbetween entrance nodes is possible;

FIG. 4 is an overhead view of a robot operating area;

FIG. 5 is a schematic diagram of a robot equipped with a sensor;

FIG. 6 is a diagram showing a sensor table of an entrance node;

FIG. 7 is a diagram showing a structure of an entrance node;

FIG. 8 is a sequence diagram of process contents;

FIG. 9 is a flowchart of packet processing; and

FIG. 10 is a diagram showing a table structure of a management memory.

DETAILED DESCRIPTION OF THE INVENTION First Embodiment

One embodiment for carrying out the present invention is shown in FIG.1.

A network system of the present exemplary embodiment is a system thatuses a wide area network connecting plural companies' hubs and the like.The network system is composed of a data center (10), a wide areanetwork (11), plural entrance nodes (12), plural sensor nodes (13), andplural actuators (14). In this network system, data generated from theplural sensor nodes 13 is collected to the data center 10 via theentrance nodes 12 and the wide area network 11 and the data is stored ina lump and subjected to computational processing or the like in the datacenter 10.

Plural sensor nodes 13 exist in each hub and there is a variety of typesof sensors such as temperature sensors, humidity sensors, vibrationsensors, pressure sensors, motion sensors, microphones, and cameras. Thesensor nodes 13 and the entrance nodes 12 are connected, respectively,via wired or wireless communication lines.

The entrance nodes 12 are network nodes that are located at theentrances of the wide area network and communication devices thatperform decision processing and computational processing functionsbesides switching and router functions. These entrance nodes 12 areinstalled per room, per floor, per building, and per hub, depending onthe number of sensor nodes 13 attached to an entrance node, processitems required to be executed by an entrance node, etc., besides theperformance of an entrance node itself. Although it is not necessarythat all the entrance nodes 12 have comparable performance, the entrancenodes 12 are in a parallel relationship, that is, they are not deployedsuch that one entrance node embraces an area managed by another entrancenode. Therefore, three entrance nodes (shown in FIG. 1) each should havecomparable performance.

An entrance node 12 is intended to manage sensor nodes connected to it,and to monitor transmission data transmitted by the sensor nodes andperform computational processing on the data. By data monitoring andcomputational processing as above, one purpose of the entrance node isto reduce traffic and reduce the load of the wide area network 11 byperforming filtering processing which is a general term forcomputational processing such as compression, selective deletion,averaging, etc. of data to be transmitted onto the wide area network 11.Also, the entrance node has another purpose as noted below. If a quickresponse is required, the entrance node 12 gets a result ofcomputational processing and sends various types of actuators 14connected thereto a signal for operating these actuators. The reason forthis is that the actuators 14 are operated according to a result ofprocessing performed by the data center 10 in usual processing and, inthis case, there is more delay for the time taken to transfer datato/from the data center.

An overview of a sensor management table that an entrance node 12 hasfor carrying out the above management is shown in FIG. 6. The sensormanagement table of the entrance node of the present exemplaryembodiment includes information for management such as a uniquedesignation 610 to identify a sensor and the type 620 of the sensor. Aphysical port 630 to which the sensor device is connected and its IPaddress 640 are used as information to identify the sensor. The tablealso includes the IP address of a server or the like in the data center10 as a destination 650 to which information for the sensor istransmitted. Further, in the columns of process item 660 and processingnode 670, information is specified for a process item 680 and anexecuting entity (processing node) 690 of computational processing whichis performed by an entrance node.

In a case where a sensor node moves, a behavior using the presentexemplary embodiment is described below. FIG. 2 shows a configuration ina case where some sensor nodes moved from the state of FIG. 1. At thistime, due to the movement of the sensor nodes, the entrance nodes towhich they are connected alter. This assumes, for example, a case wherethree entrance nodes are installed in a distributed manner in acompany's hub and machine tools equipped with the sensor nodes attachedto the entrance nodes moved because of relocation for use.

In FIG. 2, a sensor node 13-3 is connected to an entrance node 12-1 anda sensor node 13-4 is connected to an entrance node 12-3. Thereby, thereis no sensor node that is directly connected to an entrance node 12-2.

If such a situation occurs, operation in the present exemplaryembodiment is based on a scheme that differs from the way in which anadministrative server existing in the data center or the like copes withthe management of the entrance nodes by updating the sensor node tablesheld by the entrance nodes and process items to be handled in anintegrated fashion. Specifically, in an example of FIG. 2, the entrancenode 12-1 becomes responsible for filtering processing for the sensornode 13-3 in addition to sensor nodes 13-1, 13-2.

In this case, one problem is that the entrance node 12-2 has becomeunable to make use of its computational processing capacity, becausethere has been no sensor node managed by it. Another problem is that, iffiltering was performed on both sensor data from sensor nodes 13-3, 13-4managed together by the entrance node 12-1 before the relocation, thedestination of these data is separated into the node 12-1 and the node12-3 after the relocation and, thus, filtering of the data from thesensor nodes 13-3, 13-4 can only performed after collected to the datacenter. Of course, this may occur in a situation of FIG. 1 before therelation occurs. For example, filtering and the like could not beperformed together for data from a sensor node 13-1 connected to theentrance node 12-1 and data from a sensor node 13-6 connected to theentrance node 12-3. The latter problem is due to the fact that there isno cooperation among the entrance nodes. However, if the sensor nodesare statically located, the problem would be resolved by consideringdeployment of the entrance nodes and allocation of the sensor nodestogether with making effective use of the computational processingcapabilities of the entrance nodes, as mentioned above.

In the present exemplary embodiment, this problem due to the relocationof the sensor nodes is resolved by means of cooperation among theentrance nodes and the sensor table shown in FIG. 6.

In a case that the connection destinations of the sensor nodes havealtered from the state of FIG. 1 to the state of FIG. 2, the entrancenodes 12-1 and 12-3 having received communications from new sensor nodesreceive management information for these sensor nodes by communicatingwith other entrance nodes known by them to exist in the neighborhood.More specifically, the entrance node 12-1 sends a query to the nodes12-2 and 12-3 and the entrance node 12-3 sends a query to the nodes 12-1and 12 2 about information for the sensor nodes 13-3 and 13-4 newlyconnected thereto. At this time, the entrance node 12-2 that managed thesensor nodes 13-3, 13-4 sends back information existing in its sensortable to the entrance nodes that sent the query, respectively.

The entrance nodes 12-1 and 12-3 having received the reply take overinformation about filtering processing that has so far been performed bythe entrance node 12-2 by updating their sensor management tables. Also,it thus becomes unnecessary to send a query to an administrative node orthe like existing in the data center 10 about the management of thesensor nodes.

Moreover, in the present exemplary embodiment, cooperative operationamong plural entrance nodes is carried out by using the sensor tableshown in FIG. 6. In FIG. 6, each entrance node holds a process item 660for a sensor and information 670 for a node that executes the process,which are associated with each other and stored. Thereby, an entrancenode holds not only process items for which it is responsible, alsoknows process items that are executed by other neighboring entrancenodes, so that it can get knowledge of some other entrance node thatneeds information for the sensor. Therefore, it becomes unnecessary tosend a query to the data center.

In FIG. 6, it is assumed that an entrance node labeled EN1 holds thissensor table and nodes EN2, EN3 exist in its neighborhood. At this time,all data from sensors 1 to 4, namely, temperature sensors is transmittedto an IP address “100.xx.xx.1”. At the same time, an average value ofdata from four sensors is calculated at EN1 as averaging 1. Further, itcan be seen in “process item 2” that an average value for a given periodof time for each temperature sensor is calculated at EN1. As for sensors5 to 8, namely, humidity sensors, the destination IP address of theirdata is “100.xx.xx.2” and, moreover, averaging 2, which is averagingamong humidity measurements, is performed. As for sensors 9 to 12,namely, vibration sensors, their sensor data is not transmitted to aparticular IP address and compression processing on data from each ofthese sensors is executed at EN1. This is because, the vibration sensorsare only assumed to send a larger amount of data than other sensors. Asregards the vibration sensors, at the same time, information isspecified that data from the sensors 9 and 10 is used for abnormalitydetection at EN2 and data from the sensors 11 and 12 is used forabnormality detection at EN3. Thus, EN1 receives and compressesvibration data from these sensors and also transfers this data to thecorresponding EN2, EN3.

When an entrance node holds the table like this, if it receives datafrom a new sensor, it sends a query to other entrance nodes. The tableis updated by receiving information existing in the management table ofthe source entrance node from which the sensor node moved. Here, thefollowing description focuses on the behavior of the source entrancenode from which the sensor node moved, instead of the entrance node towhich the sensor node moved newly.

For example, a case where a sensor 4 associated with EN1 in FIG. 6 ismoved to EN2 is considered. The sensor 4 is a sensor for which anaveraging process and a time average calculation process on data from ithave so far been performed at EN1. EN1 detects that no information hasbeen arrived from the sensor. However, once the sensor has moved to aneighboring entrance node, a notification from the neighboring entrancenode may sometimes arrive before the detection. This is because, todetect, for example, an abnormality occurred in the sensor for anyreason such as a fault occurrence, EN1 knows it only after anticipateddata transmission failed or communication failed a certain number oftimes. Consequently, in a situation where the sensor is moving, theneighboring entrance node, EN2 in this case, is likely to detect a newsensor not managed by EN2 and send a query to other entrance nodes at anearlier point of time. However, if the sensor node has placed in noresponse state due to a fault occurrence, not relocation, EN 1 havingdetected the abnormality normally requests the administrative node tomake a decision.

When EN1 having received the query about the sensor 4 from EN2 finds thesensor with the relevant IP address existing in its table, EN1 sendsback information about the sensor 4 it has to EN2. Thereby, EN2 sharesthe history and state of processing operation of EN1, i.e., whatprocesses have been executed for the sensor 4 until now, and takes overthe processes. According to an example of FIG. 6, it can be seen that“averaging 1” and “time average 4” have been executed. At this time,“time average 4” has so far been executed by EN1 based on data only fromthe sensor 4, whereas, for “averaging 1”, EN1 has used data from othersensors 1 to 3, namely, temperature sensors. Thus, in this case, EN2sends a query again to the entrance node that managed data from thesensors for “averaging 1” and performs allocation with respect to thedata from the sensors.

This allocation is determined by the type and number of sensors managedby the entrance node and numeral allocation of sensors that are addedand sensors that have already being managed. For example, on account ofthe fact that data from three of the four sensors is processed by EN1and processing resources have been deployed at EN1 because EN1 hasexecuted the process “averaging 1”, EN2 is to transfer temperature datafor averaging to EN1. On the other hand, “time average 4” is acomputational process based on data only from the sensor 4 and EN2 takesover this process without transferring data.

Process allocation is configured, based on the loads of the entrancenodes, besides the number of sensors managed by each entrance node. Forexample, if EN2 is already responsible for quite a large number ofcomputational processes and is put under a large load, allocation offiltering process items may be reconfigured between EN1 and aneighboring entrance node from a perspective of load distribution. Forthis reconfiguration, an entrance node may obtain the processing statesof other entrance nodes and perform the reconfiguration or the datacenter or the administrative node may perform the reconfiguration.

By performing this reconfiguration of filtering processes, taking theloads into consideration, to an entrance node having surplus resourcesand processing performance because no sensor node managed by it has beenmissing, like the entrance node 12-2 in FIG. 2, other nodes may transfera filtering process and data obtained from the sensors, so that theentrance node executes the process newly. In this way, effective use ofprocessing resources throughout the system can be achieved.

In the example of FIG. 6, EN2 and EN3 receive data from vibrationsensors and perform abnormality detection. The reason why these nodes doso is thought to be that an actuator for an alarm or the like to beoperated upon detecting an abnormality is connected to EN2 and EN3, likethe nodes 12-1 and 12-3 in FIG. 1. Like this, an entrance-node-specificcondition may sometimes be a factor for determining which entrance nodeshould execute a filtering process.

When an entrance node transfers data for filtering to another entrancenode, it is conceivable to execute a pre-filtering process beforehand,depending on a filtering process item that is executed by the transferdestination node. By executing such process, more efficient use ofnetwork bandwidth and computational performance is possible, as comparedwith simple load balancing.

As shown in FIG. 3, all entrance nodes may be connected with dedicatedlines between them, so that communication is performed between entrancenodes. These lines are not used for normal data transfer, but are usedonly for communication between entrance nodes in consequence of sensornode relocation and for transfer of data obtained from sensor nodes fromone entrance node to another entrance node. This enables high-speed andreliable communication between entrance nodes without taking care ofloops and without affecting the bandwidth of the wide area network 11situated upstream. In particular, because a distance between entrancenodes from/to which a sensor node is anticipated to move is physicallylimited, it is conceivable that these nodes can be connected by ashort-distance and high-speed line and, thus, its effect is expected tobe high. By performing data transfer through this line, it is possiblethat an entrance node from which a sensor moved takes over the role oftransfer, making an upstream network entity unaware of the sensorrelocation.

FIG. 7 shows an example of an internal structure of an entrance node 12which is a network node included in the system described above. Theentrance node includes a network interface 1201-1 connecting to the widearea network as a network interface (1201) for connection to a network,a network interface 1201-2 for connection to a sensor node, and anetwork interface 1201-3 for EN-to-EN communication.

The entrance node further includes a process item finding unit (1202)that finds a process item from the contents of a packet, a destinationfinding unit (1203) that determines a destination to which data is to betransmitted, a data processing unit (1204) that executes computationalprocessing using data from a sensor node, such as filtering, a sensortable (1205) for management of the addresses of sensors, a destinationtable (1206) for management of destination information, a time stampattaching unit (1207) for attaching time stamp information to a receivedpacket, a management memory (1208) for management of contents such asfiltering processes and destinations, a timing management unit (1209)for reading timing information of a packet which is transmitted andreceived between ENs, and a sensor table updating unit (1210) thatexecutes sending a query about sensor information to another EN andreceiving its reply. Packets received from a sensor node and the widearea network via the respective network interfaces 1201 are passed tothe process item finding unit 1202. Further, a load monitoring unit(1211) monitors the processing load of the data processing unit 1204 andhas a role of updating load information per process to the managementmemory 1208 and sending a signal indicating a high load state to thesensor table updating unit 1210. There is also a packet buffer (1211)for holding a packet during an update of the sensor table and themanagement memory.

The process item finding unit 1202 refers to header information such asinformation for an input port of the traffic included in a packet and anIP address, searches the sensor table 1206 based on the headerinformation, and decides how to handle the packet according to thesearch result.

By the decision, if the packet is to be transferred, the packet isdirectly sent to the destination finding unit 1203. By the decision, ifit has been decided that a computational process such as filtering isneeded, the packet is transferred to the data processing unit 1204. Thedata processing unit 1204, upon receiving the packet, determines aprocess item for the packet by searching the management memory 1208,executes the process identified by the determination, and then transfersthe packet to the destination finding unit 1203. The destination findingunit 1203 receives the packet, searches the destination table 1206, andselects a destination by the search result.

The management memory 1208 has a table 1000 which is shown in FIG. 10.The table of the management memory includes a process No. (1010) fornumber management of each process, a process item 1020 representing aspecific process name, a sensor designation 1030 of a sensor which isused for the process, a task designation 1040 of a task which is usedfor the process, stored data 1050 which is used for the process, anexecution period 1060 of the process, the amount of a load 1070 measuredin executing the process, movability 1080 indicating whether the processitem can be moved, and destination information 1090 to which a resultobtained by executing the process is to be sent.

FIG. 8 is a sequence diagram showing a process flow upon receiving apacket. The process item finding unit 1202 searches the sensor table1205-1 to see whether a sensor designation, sensor type, connectionport, and IP address included in the received packet are registered inthe table. As a result of searching the sensor table 1205-1 by theprocess item finding unit 1202, if information included in the packetdoes not exist in the sensor table 1205-1, the process item finding unit1202 requests the sensor table updating unit 1210-1 for a query aboutthe non-existent information. The sensor table updating unit 1210-1sends a query to some other entrance node existing in the neighborhoodvia the network interface for EN-to-EN communication to shareinformation about a new sensor.

On the other hand, the some other entrance node having received thequery from the sensor table updating unit 1210-1 likewise passes themessage to its sensor table updating unit 1210-2. The sensor tableupdating unit 1210-2 searches the contents of the sensor table 1205 tocheck whether the sensor information exists in the table. If therelevant data exists in the sensor table, the sensor table updating unit1210-2 searches the table of the management memory 1208-2 based onsearch criteria of a process item and obtains information for a processrelated to the packet. The sensor table updating unit 1210-2 sends backinformation including the load, movability, etc. of the process itemexisting in the table of the management memory 1208-2 to EN1.

The sensor table updating unit 1210-1 of the entrance node EN1 that sentthe query, upon receiving the reply, updates the sensor table 1205-1 andthe management memory 1208-1, based on the information contained in thereply. Then, the sensor table updating unit 1210-1 decides whether EN1is to take over the filtering process or transfer data from a new sensornode that has just moved and attached to EN1, based on a combination ofthe information sent back from EN2 and the load information existing inthe management table. This decision is also notified from the sensortable updating unit 1210-1 to the sensor table updating unit 1210-2 ofthe some other entrance node, so that rewriting of the sensor table1205-2 and the management memory 1208-2 is performed. During therewriting, a new entry is created in the sensor table 1205-1, thecorresponding entry in the management table 1208-1 is migrated as isfrom EN2 to EN1, and the process item name and the load information areupdated. Also, a handover of the relevant stored data is performed totake over the process item. After a series of these notifications, thesensor table updating unit 1210-1 instructs to send back transferdestination information to the process item finding unit 1202, based onthe updated information in the sensor table 1205-1 and a packet transferis executed by the process item finding unit 1202.

A flow is described in a case where the above decision is not to handover the filtering process, instead, to transfer the packet received bythe entrance node to some other entrance node. In this regard, forpacket transfer, one way is transferring the packet without executing afiltering process on the packet and another way is transferring thepacket after executing a filtering process on the packet.

When transferring the packet without executing a filtering process onthe packet, the process item finding unit makes the transfer decision.The process item finding unit 1202 passes the packet together with thetransfer destination information of the packet to the time stampattaching unit 1207. After the time stamp attaching unit 1207 attachesto the packet time information (a time stamp) about timing at which theentrance node received that packet, the packet is transferred to anentrance node that is the destination of transfer via the networkinterface 1201-3 for EN-to-EN communication.

On the other hand, when transferring the packet after executing afiltering process on the packet, the data processing unit 1204 makes thetransfer decision. The data processing unit 1204 executes a filteringprocess required for the packet to be transferred and then transfers thepacket to the timing management unit 1209, and the timing managementunit 1209 attaches time stamp information to the packet.

The entrance node having received the transferred packet through thenetwork interface 1201-3 for EN-to-EN communication passes the packet toits timing management unit 1209. At this time, the timing managementunit 1209 compares timing information with the transfer source entrancenode and monitors for an incorrect order of arrival timing in a casewhere packets arrive from plural entrance nodes. Depending on a resultof the monitoring, the timing management unit 1209 may perform thefollowing action: storing packets, reordering packets, or discarding apacket. The timing management unit 1209 further passes the receivedpacket to an intelligent processing unit 1204 and the intelligentprocessing unit 1204 executes a filtering process on this packet, whilereferring to information in the management memory 1208, as does for anormal packet.

The foregoing is description with regard to FIG. 7. In a case thatdedicated network lines between entrance nodes do not exist, as inexamples of FIG. 1 and FIG. 2, the network interface 1201-3 does notexist and all traffic to be transferred is transmitted and receivedthrough the destination finding unit and via the network interface1201-1 with the wide area network.

FIG. 9 is a flowchart of processing in an entrance node 12.

The process item finding unit 1202 of the entrance node 12-1 receives apacket from a sensor node (910). The process item finding unit 1202searches the sensor table 1205-1 to see whether a sensor designation,sensor type, connection port, and IP address included in the receivedpacket are registered in the table (920).

As a result of the search, if those are not registered in the sensortable 1205-1 (No, 930), the sensor table updating unit 1210-1 sends aquery to other entrance nodes 12-2 and 12-3 via the network interfacefor EN-to-EN communication (930, 940).

In one or more other entrance nodes including an entrance node 12-2,having received the query, if relevant information has been found (Yes,950) in at least one of these nodes, the entrance node 12-1 receives therelevant information from the entrance node having that information.Then, the entrance node 12-1 stores the received information into a newentry, respectively, in the sensor table and the management table.Further, based on information for a process item obtained, the entrancenode 12-1 decides whether to change the entrance node in charge ofprocessing (961). For example, the entrance node 12-1 obtains the loadsof other entrance nodes 12-2, 12-3 and compares each of these loads withthe load of the entrance node 12-1 itself. The entrance node 12-1decides whether to change process allocation. For example, the processitems for which the entrance nodes are responsible, respectively, may beinterchanged for optimization for the purposes of equalizing the loadsamong the entrance nodes and reducing communication traffic. Allocationchange decision may be made by, for example, sending a query to anentrance node having the right to make this decision or a database. Bythe decision, it is decided that changing the entrance node in charge ofprocessing is needed (Yes, 961), the entrance node 12-1 notifies otherentrance nodes of the change and reallocating process items among pluralentrance nodes is performed (962).

The entrance node 12-1 refers to the sensor table and changesinformation for a processing node 670 in the entry of a process forwhich reallocation has been performed to that for an entrance node thathas now become responsible for the process. The entrance node 12-1 alsodeletes the entry of a process in which it is no longer engaged from themanagement table (963). Further, the entrance node 12-1 notifies thedata center that the entrance node in charge of processing changed.After finishing these updates or if no allocation change is needed (No,961), the entrance node 12-1 searches the sensor table again (970).

On the other hand, if information about the input packet does not existin other entrance nodes at step 950, the entrance node 12-1 regards itas a new entry and adds an entry related to the relevant sensor to thesensor table and the management table by, for example, sending a queryto the data center (951). After thus creating a table entry related to aprocess item that is executed, searching the sensor table 970 isperformed.

As a result of searching the sensor table (920), if information aboutthe relevant input traffic exists in the sensor table (Yes, 930), as aresult of searching the sensor table that has been updated 970, theentrance node 12-1 decides whether it is needed to transfer thatinformation to other entrance nodes by referring to the processing nodecolumns 670, 690 in the entry relevant to the sensor table (980). Iftransferring that information is needed (Yes, 980), the time stampattaching unit of the entrance node 12-1 attaches a time stamp to thepacket to be transferred (981). The packet attached with the time stampis transferred to a transfer destination entrance node according to theprocessing node information referenced via the EN-to-EN communicationinterface 1201-3 (982).

If transferring that information to other nodes is not needed (980), ahighly functional process is executed, as required, for the packet bythe data processing unit (990), referring to the process item columns660, 690 in the sensor table, and a transfer destination is searched forby the destination fining unit (991). Finally, transfer to the datacenter is performed via the network interface 1201-1 (992). Theforegoing is description with regard to an exemplary first embodiment.

Second Embodiment

An exemplary second embodiment which is an example of modification tothe exemplary first embodiment is then described.

FIG. 4 shows a system structure in a factory. In the whole area shown,there are a robot operating area (40) for robot terminals to operatewithin it, entrance nodes (41), radio network base stations (42)operating in that area, and an administrative server (43) for integratedmanagement of information from the entrance nodes 41. Besides, althoughnot shown in FIG. 4, robot terminals, respectively, equipped withvarious types of sensors can move within this robot operating area 40.Thus, the robot terminals correspond to the sensor nodes in theexemplary first embodiment and send their sensed information to theentrance nodes (41) which are capable of radio communication with therobot terminals. Each entrance node has the structure shown in FIG. 7with regard to the exemplary first embodiment and collects data fromeach robot by radio via the network interface 1201-2. Also,communication between the entrance nodes 41 is performed via EN-to-ENnetwork interfaces 1201-3. Other processing details are the same as forthe exemplary first embodiment.

In the management table 1000 of an entrance node, at this time, varioustypes of processes for controlling robot operation such as controllingthe front wheel and rear wheel motors of a robot, detecting an obstacle,preventing collision with another robot or something are added asentries. These various types of processes and other data including imagedata obtained by a camera 504 of each robot terminal 50 and temperaturedata measured by an environmental sensor are stored in the entries ofthe table of FIG. 6 and the table of FIG. 10, as is the case for theexemplary first embodiment.

According to the present exemplary embodiment, the robot operating area40 is divided into four areas. The number of area divisions depends onthe performances of the entrance nodes 41, the performances of the radionetwork base stations 42, the number of the robot terminals existing inthe area, etc. A single entrance node 41 performs management of eachdivided robot operating area 40 and radio network base stations 42within that area are also connected to the entrance node that performsthe management of the area. Each of these radio network base stations 42serves to transmit all received traffic to the entrance node and totransmit a signal from the entrance node to a robot terminal.

A robot terminal (5) which is shown in FIG. 5 is configured with a radiomodule (501), a battery (502), an environmental sensor (503), a camera(504), a front wheel motor (505), a rear wheel motor (506), and a linetracing camera (507). The radio module serves to communicate with aradio network base station 42 deployed in the area and is also used fordetecting location information by measuring a delay between signals fromplural radio network base stations 42 at the entrance node 41. Thebattery 502 is a rechargeable battery for driving the whole robot; inaddition to supplying power throughout the robot terminal, the batterymonitors its remaining amount of power and notifies it to the entrancenode 41.

The environmental sensor 503, by collecting information aboutenvironment such as temperature information inside and around the robot,is used to collect environmental information within the robot operatingarea and detect an abnormality such as overheat of a single robot unit.The camera 504 is a camera disposed in the front of the terminal and isused to detect an obstacle or another robot terminal from image datacaptured by it in a travel direction of the terminal. The front wheelmotor 505 and the rear wheel motor 506 are used to move the robot. Theline tracing camera 507 is a camera for recognizing basic course indexlines drawn on the floor so that the robot can locate its position andmove.

Control of a robot terminal 50 is complex and diverse and, therefore, isimplemented in such a manner that the burden for control is shared byplural entrance nodes 41. While an individual entrance node isresponsible for control of an individual robot, it is preferable thatthe entrance nodes communicate with each other as required. There is aprocess item that is processed by an entrance node itself; a process asdescribed in step 990 in FIG. 9 corresponds to this. On the other hand,information for the battery's remaining amount and information such as ause rate of a power feeding station are preferably managed by a singleentrance node in an integrated fashion. This corresponds to a process asdescribed in steps 981, 982 in FIG. 9.

In a case where many robot terminals have come together in a particulararea, the entrance nodes communicate with each other for loaddistribution processing, e.g., entrusting control to an entrance nodethat supervises another area. This load distribution processingcorresponds to a process as described in steps 961, 962, 963 in FIG. 9.For load distribution, each entrance node calculates integral values ofthe execution periods and the amounts of load of the processes for whicheach node is responsible and notifies the integral values to each other.Based on relative comparison of the integral values, a process item andits processing node are determined, also taking a data route or the likeinto consideration. There is a need for combining plural pieces ofinformation obtained by various types of sensors regarding control thatmanages basic robot operation. Hence, it is more efficient that a singleentrance node processes a set of such pieces of information per robot.Such information set obtained by sensors includes location informationof the radio module 501, images captured by the camera 504 and the linetracing camera 507, management of the operations of the front wheelmotor 505 and the rear wheel motor 506, etc.

In a conceivable manner, as for a set of information obtained by thesensors on a robot, an entrance node nearest to the robot ispreferentially responsible of processing the set of information. In thiscase, “movability” 1080 is set to “yes” in the entry as to the relevantprocess in the management table 1000. The entrance node 12 refers to the“movability” flag 1080 in the relevant entry in the management table andit hands over the entry including the process item to another entrancenode, when the robot has moved into a different entrance node's areaacross the boundary of the area. At this time, if the robot mobilitybetween different areas is less frequent and if the robot is less likelyto return after having once moved, an effect of reducing the frequencyof communication between entrance nodes can be obtained. A migrationprocess at this time corresponds to steps 961, 962, 963 in FIG. 9.

In another conceivable manner, a single entrance node is staticallyresponsible for processing per robot. In this case, “movability” 1080 isset to “no” in the entry as to the relevant process in the managementtable 1000. According to this manner, even when the robot has moved outof the area, the entrance node gets information from the robot terminal50 via another entrance node. Therefore, there is an advantage that itis not needed to hand over the processing responsibility itself betweenentrance nodes. That is, this is a manner represented in FIG. 9 suchthat allocation is not changed in step 961 and processing is only doneby packet transfer to other entrance nodes in steps 981, 982.

Alternatively, by jointly managing robot control information by pluralentrance nodes, processing is performed using data shared in the sensortable and the management table for location management such aspreventing collision between plural robots and a control handover when arobot moves from one area to another area. According to this manner,management of a robot located near to a boundary between plural areas isimplemented by sharing information and control process items for therobot by the entrance nodes supervising these areas.

On the other hand, because of a positional factor other than robots,there is a process that is preferably executed by a particular entrancenode. For example, management of battery charging states is performed byan entrance node that supervises an area in which a charging stand issituated. The entrance node collects the use state of the batterycharging stand and the battery use states of all terminals. Accordingly,to this entrance node, all other entrance nodes transmit batteryinformation collected by them. Such transmission corresponds to aprocess as described in steps 981 and 982 in FIG. 9.

As another item to be monitored, there is environmental information thatis collected by environmental sensors. For these pieces of information,after their data amount is once reduced by filtering or othermanipulation at each entrance node, the information is transmitted to aparticular entrance node for executing abnormality monitoring. In somecases, the entrance node that executes abnormality monitoring may be anentrance node to which any type of actuator for warning of a specificabnormality is associated. In another case, an entrance node having theleast load may simply be chosen as such entrance node. Terminals otherthan the particular entrance node transmit data that is used forabnormality monitoring to the particular entrance node through a processas described in steps 981 and 982 in FIG. 9.

1. A network system comprising: an information processing device thatmanages status of an object to be monitored; a plurality of sensingdevices that senses information of an object to be monitored; and afirst network node that receives a packet from at least one of thesensing devices, decides whether a node that executes a computationalprocess on information in the packet is identifiable, and, if it hasbeen decided that such node is not identifiable, sends a query about thecomputational process on information in the packet to some other node.2. The network system according to claim 1, wherein the some other nodeis a second network node connected to the information processing devicevia a network and capable of communication with at least one of thesensing devices, and wherein the first network node receives a reply tothe query from the second network node and executes the computationalprocess relevant to the packet, based on the reply.
 3. The networksystem according to claim 2, wherein the computational process is acomputational process to be executed on a plurality of packets, andwherein the first network node receives the reply including a history ofpervious computational processes and executes the computational processbased on the history of computational processes and the packets.
 4. Thenetwork system according to claim 3, wherein the first network nodetransmits a result of the execution of the computational process to theinformation processing device.
 5. The network system according to claim4, wherein the packet includes information sensed by a sensor withrespect to the object to be monitored, and wherein the computationalprocess is a computational process to be executed on the informationsensed by the sensor.
 6. The network system according to claim 1,wherein the some other node is a second network node connected to theinformation processing device via a network and capable of communicationwith at least one of the sensing devices, and wherein the first networknode transmits the packet to the second network node.
 7. The networksystem according to claim 6, wherein the first network node storesinformation for a transfer destination of the packet.
 8. The networksystem according to claim 1, wherein the some other node is a secondnetwork node connected to the information processing device via anetwork and capable of communication with at least one of the sensingdevices, and wherein the first network node receives a reply to thequery from the second network node and decides which network node shouldexecute the computational process on the packet, based on a load of thesecond network node included in the reply and a load of the firstnetwork node itself.
 9. The network system according to claim 8, whereinthe first network node holds information about a network node thatexecutes the computational process on the packet according to thedecision and transfers a further received packet based on the heldinformation.
 10. A packet processing method in any one of a plurality ofnetwork nodes capable of executing a computational process on a packet,comprising: receiving data obtained by sensing an object to be monitoredfrom a sensing device; deciding whether a process to be executed on thedata is allocated; if the process is not allocated, sending a query tosome other network node; deciding whether to transfer the packet to someother network node or allocate a computational process on the packet tothe network node itself according to a result of the query; andexecuting the packet processing according to the decision.
 11. A networknode comprising: a first network interface that is connected to a sensornode via a first network; a second network interface that is connectedto an information processing device via a second network; a thirdinterface; a storage unit for storing information about a computationalprocess on information included in a packet; and a control unit that,when a packet has been transmitted by the sensor node and if informationincluded in the packet is not stored in the storage unit, sends a queryto some other network node via the third interface and decides whetherto entrust the computational process on the packet to the some otherentrance node or execute the computational process by itself accordingto a reply to the query.